Digital computer theort training machine



Dec. 29, 1964 F. G. ELMLINGER 3,152,960

DIGITAL COMPUTER THEORY TRAINING MACHINE Fil ed Sept. 10, 1962 5Sheets-Sheet 2 N (mark N on v N @i 7 $27 ym; in; W

N INVENTOR. FRANK G. ELMLINGER Dec. 29, 1964 F. G. ELMLINGER 3,162,960

DIGITAL. COMPUTER THEORY TRAINING MACHINE Filed Sept. 10, 1962 5Sheets-Sheet 3 INVENTOR. FRANK G. ELMLINGER United States Patent OfficeBJSZEW Patented Dec. 29, lgfi i 3,162,960 DliGTTAlL COMPUTER MA-DHTNEFrank G. Eimiinger, San Diego, (Ialifi, to Sherry @riswoid Foundation,business as Electronic Technical institute lFiie Sept. 1%,1962, Ser.No.-222,6d 7 Claims. (Ci. SS -3d) TRATNTNG This invention relatesgenerally to training aids and devices and more particularly to a devicethat provides training in design of digital computer switching circuitsfor conversion of numbers from one system to another in the binary,octonary and decimal number systems.

Background Digital computer switching circuits are provided in variousforms and combinations, all well known to the art. A majority of digitalcomputers perform computations in the binary number system, a simplecounting system that contains only two digits, 0 and 1. Since thedecimal numbersystem, containing the digits 0 through 9, is useduniversally for arithmetical operations, digital computers must becapable of converting input data from the decimal to the binary numbersystem before performing computations. Then, after performingcomputations in the binary number system, digital computers must becapable of converting output data from the binary to the decimal numbersystem.

Switching circuits used in digital computers for conversion of numbersfrom one system to another use electronic components such assemi-conductor diodes, monostable multivibrators, magnetic cores,relays, and so on. Such circuits operate with speeds measured infractions of a microsecond. Consequently, operation of digital computerswitching circuits is not observable except in comparing input data withoutput data.

This invention enables students to design and construct switchingcircuits composed of manually operated switches, semi-conductor diodes,and resistors. The switching circuits operate visual display devicesthat compare input data with output data and enable students to checkthe accuracy of switch settings and to make switching changes whennecessary, Additionally, voltage test points enable students to measurevoltages at various points in the switching circuits andverify that theswitching circuits are operating in accordance with design principles.

For example, to convert binary datalOOl to an equivalent decimal digit9, binary digit selector switches are set so that'the binary digitdisplaydevice displays the digits 1001. Then the decimal digit selectorswitches are set so that the decimal digit display device displays thedigit 9. Only one combination of switch settings will provide these twodisplays. An error in one switch setting will cause an error in onedisplay or the other.

Objects It is a principal object of this invention to provide a trainingdevice that enables students to design and construct a pluralityofnumber conversion switching circuits.

It is another object of this invention to provide a training device thatdisplays digits in the binary, octonary, and'decimalnumber systems forcomparison of one system with another.

It is still another object of this invention to provide a trainingdevice that enables students to verify that number conversion switchingcircuits are operating in accordance with design principles.

With these and other objects definitely in View, this invention consistsin the novel combination and arrangement of elements as will behereinafter fully described in the specification, particularly pointedout in the claims,

and illustrated in the drawings that form a material part of thisdisclosure, and of which:

FIGURE 1 isa functional block diagram; and

FiGURES 2A and 2B are portions of a schematic diagram of this invention.

Similar characters of reference indicate similar or identical parts andportions throughout the several views.

The various elements of this invention are mounted on a panelapproximately as shown in FIGURE 1. The illustrated number of tubes andswitches is, of course, exemplary only of one practical embodiment ofthe invention. Direct current operating voltage for the panel is appliedby Operating Mode Selector 1% to four Binary Digit Display Tubes 12, aDecimal Digit Display Tube 14, and No. 1 Octonary-Decimal Digit SelectorNo. 16. Operating Mode Selector it) is a 6-position, S-deck rotaryswitch that provides five operating modes as shown, Binary DigitSelector 18 is an assembly of 44 single-pole, double-throw switchesarranged in four ll-switch groups, one group for each Binary DigitDisplay Tube 12. The top set of four. switches labeled B is used toselect 0 or 1 digits for display by each of the four Binary DigitDisplay Tubes 12 when No. 2 Octonary-Decimal Digit Selector 20 is in theposition labeled B. This No. 2 Octonary-Decimal Digit Selector 2t?- isanll-position, 5 deck rotary switch-that causes the corresponding digits0 through 9 to be displayed by Decimal Digit Display Tube 14, when theswitch is in one of the O through 9 positions. One of the 4-switch setslabeled 0 through 9 in Binary Digit Selector 18 is used to select 0 or 1digits for display by each of the four Binary Digit Display Tubes 12when Octonary-Decimal Digit Selector No. 2 correspondingly is in one ofthe 0 through 9 positions. The No. l Octonary- Decimal Digit Selector 16is an assembly of 40 semiconductor diodes and 44 single-pole,double-throw switches arranged in four ll-switch groups, the four groupsbeing used in conjunction with the 4-switch set v labeled B in BinaryDigit Selector 118. The 4-switch set labeled B is mechanically linked tothe'4-switch set labeled B in Binary Digit Selector 113, while the4-switch sets labeled 0 through 9 are used with the semiconductor diodesto select the corresponding 0 through9 digit displayed by Decimal DigitDisplay Tube 14.

When Operating Mode Selector lit is in the Binary position No. 2Octonary-Decimal Digit Selector is placed in the B position, and the4-switch set labeled B inBinary Digit Selector lit; is used to selectthe 0 or ldigit displayed by Binary Digit Display Tubes 12. During thisoperating mode, Decimal Digit Display Tube 14 and the No. lOctonary-Decimal Digit Selector are disabled.

When Operating Mode Selector M is in the Binary- Octonary position, theother switches are used as described for the Binary Operating Mode.Additionally, Decimal Digit Display Tube lid is enabled except forthe 8and 9 cathodes, No. l Octonary-Decimal Digit Selector 16, is enabled,and the appropriate 4-switch set is used to cause Decimal Digit DisplayTube is to display the octonary digit corresponding in numerical valueto the binary digits displayed by Binary DigitTubes 12;

When Operating Mode Selector lit) is in the Binary Decimal position, theother switches are used as described for the Binary-Octonary operatingmode. Addi tionally, cathodes 8 and 9 are enabled in Decimal Digit Tube14.

When the Operating Mode Selector it) is in the Octonary Binary position,cathodes ti and 9 of decimal Digit Display Tube 14 are disabled, No. lOctonary- Decimal DigitSelector lid is disabled, and No. 2 Octonary-Decimal Digit Selector 2a is used to select the digit 0 through '7displayed by Decimal Digit Display Tube 14. Dependent on the position ofNo. 2 Octonary-Decimal Digit selector Zii, the 4 switchset with the sameposition 3 label in Binary Digit Selector 18 is used to cause BinaryDigit Display Tubes 12 to display the binary digit equivalent of theoctonary-digit displayed by Decimal Digit Display Tube 14. WhenOperating Mode Selector 1%? is in the Decimal Binary position, the otherswitches are used as described for the Octonary-Binary operating mode.Additionally, cathodes 8 and 9 are enabled in Decimal Digit Display Tube14.

Binary Mode To use this invention to demonstrate the binary numbersystem, Operating Mode Selector 10 is placed in the Binary position No.2 Octonary-Decimal Digit Selector Z is placed in the B position, andBinary Digit Selector 18 is used to select the digits displayed byBinary Digit Display Tubes 12.

Referring to FIGURE 2, switch 19A applies operating DC. to tubes12A-12D. D.C. is applied to the anodes through anode resistors 22-23 andto the cathodes through voltage dropping resistor 30 and cathoderesistors 32-46. Switch 103 connects load resistor 48 across the D.C.supply.

Switches ZtiA-ZtiD connect cathode resistors SQ-Sd to the moving arms ofswitches 58-64. Switches SS-d then are moved to one position or theother to select a 0 or 1 digit for display by tubes 12A-12D.

Binm'y-Octonary Made To use this invention to demonstrate conversion ofdigits in the binary number system to a digit in the octonary numbersystem, Operating Mode Selector 111 is placed in the Binary-Octonaryposition, No. 2 Octonary- Decimal Digit Selector 29 is place din the Bposition, Binary Digit Selector 18 is used to select the digitsdisplayed by Binary Digit Display Tubes 12, and No. l Octonary-DecimalDigit Selector 16 is used to select the digit displayed by Decimal DigitDisplay Tube 14.

Referring to FIGURE 2, switch 10A applies operating D.C. to tubes12A-12D as in the Binary Operating Mode. Switch 1013 disconnects loadresistor 48 from the D.C. supply and applies D.C. operating voltage toNo. 1 Octonary-Decirnal Digit Selector 16 through resistors 6 80. Switch111C applies operation D.C. to tube 14. D.C. is applied to the anodethrough anode resistor 82 and to the cathodes through voltage droppingresistor S4 and cathode resistors 86-104. Switches 10D and WE disconnectcathodes 8 and 9 of tube 14 from ground return through resistors 11% and168.

The eiiect and use of switches ZtlA-ZtlD and 53-6 1 is the same asdescribed in the Binary operating mode.

The moving arm of switches Mil-116 are connected mechanically to themoving arm of switches 58-64, respectively. Consequently, the binarydigits selected by switches 58-64 determines the closed position ofswitches Mitt-116. The closed positions of switches 11(1-116 completethe ground return for thusly connected resistors 66-30 and causes avoltage drop across said resistors. As a result of the voltage drops,switches 118-196 that are closed in the same positions as switches110-116 apply zero voltage to diodes 198-276. Consequently all diodesthusly connected to zero voltage do not conduct through ground returncathode resistors 1626, 103, and 278-292. For resistors 66-81 that areconnected to the open positions of switches 11tl-116, the ground returnpath is through switches 118-196 that are closed to the open positionsof switches 116-116. In this case, diodes 1%- 276 connected thereto doconduct through resistors 11%, 1118, and 280-292 connected thereto. Thevoltage drop developed across any resistor 106, 108, and TESS-292prevents the cathode connected thereto from illuminating and displayingthe associated digit in tube 14. Consequently, for tube 14 to displaythe octonary digit equivalent of the binary digits displayed by tubes1211-1213, all four switches connected through diodes to the cathodethat controls the desired octonary digit are closed in the same closedpositions as switches 110-116, and at least one switch in each of theother 4-switch sets that are connected through diodes to the othercathodes must be closed in the open position of one of switches1119-116.

Binary-Decimal Mode Operation of this invention to demonstrate binary todecimal digit conversion is the same as for the Binary- Octonaryoperating mode except Operating Mode Selector 19 is placed in theBinary-Decimal position and Switches 101) and NE connect cathodes 8 and9 of tube 14- to ground return through resistors 1636 and 108.

Switch positions in FIGURE 2 illustrate conversion of the binary digits0000 to the decimal digit 0. Switches 53-64 are closed in the 0 cathodeposition enabling tubes 12A-12D to display the binary digits 0000.Switches 1111-1116 are closed to the same relative positions as switches58-64, completing the ground return path for esistors d8, '72, 76, andSt Switches 118-124- are closed to the same closed positions as switches11(9-116, diodes 1.9842 5% are non-conducting, the voltage dropdeveloped across cathode resistor 2'78 is determined by current flowingthrough resistors 2'78, 86, and 84, and the 0 cathode of tube 14 enablestube 14 to display the decimal digit 0.

In the 4-switch set that controls the 8 cathode of tube 14 consisting ofswitches 132-183, switch 182 is closed to the open position of switch110 causing diode 268 to conduct through resistors 1118 and 66 anddeveloping an additional voltage drop across cathode resistor 108 thatdisables the 8 cathode.

Similiarly, switch 196 in the 4-sWitch set that controls the 9 cathodeof tube 14 is closed to the open position of switch 116 disabling the 9cathode. At least one switch in the 4-switch sets that control the 1through 7 cathode of tube 14 must be closed to an open position of oneof switches 11d-116. Otherwise, tube 141 will display other digits inaddition to the digit 0.

The effect of all switch settings on cathodes 0 through 9 of tube 14 maybe observed by taking voltage readings at test points 374-392 and theexposed connections of diodes Ed-276 with the movable arms of switches118- 1%. A minimum voltage reading at test point 374 indicates that noneof diodes 193-204 is conducting. This may be verified by measuring zerovoltage at each diode wit-2M. An increased voltage reading at test point3S2 indicates that at least one diode 276-276 is conducting. Individualvoltage readings at diodes 2'76- 276 indicate the conducting andnon-conducting diodes. Similar voltage readings at the other test pointsand other diodes provide indications of the operating status of allswitching combinations of No. 1 Octonary-Decimal Digit Selector 16.

Coronary-Binary Made To demonstrate conversion from octonary to binarydigits, Operating Mode Selector is placed in the Octonary-Binaryposition, No. 2 Octonary-Decimal Digit Selector 29 is placed at theposition labeled with the octonary digit 0 through 7 to be displayed bytube 14, and Binary Digit Selector 18 is used to select the binarydigits displayed by Binary Digit Display Tubes 12..

Referring to FIGURE 2, switch 10A applies operating DC. to tubes 12A-12Das in the Binary Operating Mode. Switch 16 connects load resistor 18across the D.C. supply and disables No. 1 Octonary-Decimal DigitSelector 16. Switch 10C applies operating D.C. to tube 14 as in theBinary-Octonary Mode. And switches 10D and 1GB disable cathodes t5 and 9of tube 14 by disconnecting the ground returns through positions 8 and 9of switch ZhE.

Switches MBA-D connect a 4-switch set from switches 294-372 to groundthrough cathode resistors -56, the dswitc hset so connected beingdependent on the 0 through 7 position of switches ZtlA-ZtiD. Theselected 4-switch set is used to select the combination of binary digitsdisplayed by tubes 12A-12D.

Switch ZhE connects one of the 0 through 7 cathodes q of tube 14directly to ground, dependent on the 0 through 7 position of switch245E, enabling tube 14- to display the selected octonary digit.

Decimal-Binary Mode Operation of this invention to demonstrate decimalto binary digit conversion is the same as for the Gctonary- BinaryOperating Mode except Operating Mode Selector Switch it? is. placed inthe Decimal-Binary position and switches MD and ltlE connect cathodes 8and S? of tube 14 to positions 8 and 9 of switch ZfiE.

It is understood that minor variation from the form of the inventiondisclosed herein may be made without departure from the spirit and scopeof the invention, and that the specification and drawing are to beconsidered as merely illustrative rather than limiting.

I claim:

1. In a training device for conversion of numbers from one system toanother in the binary, octonary, and decimal number systems, thecombination comprising:

first display means for visual display of digits in the binary numbersystem;

second display means for visual display of digits in the octonary anddecimal number systems;

first switching means for providing a plurality of operating modes andconnecting a D.C. source to said first and second display means;

second switching means for selecting the combination of digits displayedby said first display means;

third and fourth switching means for selecting the digit displayed bysaid second display means; and voltage measuring means for said thirdswitching means. 2. In a training device for conversion of numbers fromone system to another in the binary, octonary, and decimal numbersystems, the combination comprising:

first display means for visual display of digits in the binary numbersystem comprising a plurality of numeral indicator tubes, each havingmeans for displaying the digits 0 and 1;

second display means for visual display of digits in the octonary anddecimal number systems comprising a numeral indicator tube having meansfor displaying the digits 0 through 9;

first switching means for providing a plurality of operating modes andconnecting a DC. source to said first and second display meanscomprising a manually operated rotary switch having a plurality ofpositions and a plurality of decks, a separate position being providedfor the OFF position and each of the BINARY, BlNARY-OCTONARY, BINARY-DECIMAL, OCTONARYBINARY, and DECI- MAL-BlNARY operating modes;

second switching means for selecting the combination of digits displayedby said first display means comprising a plurality of manually operatedsingle-pole,

' double-throw switches arranged in equal groups, one group for eachnumeral indicator tube in said first display means, the fixed terminalsof all switches in each group being connected in parallel, one set offixed terminals being connected to the 0 cathode and the other set offixed terminals being connected to the l cathode of a numeral indicatortube in said first display means, the movable arms of all swtiches beingarranged to operate in equal sets, each set containing one switch fromeach group;

third switching means for selecting the digit displayed by said seconddisplay means in the BINARY- OCTONARY and BINARY-DECIMAL operating modescomprising a plurality of semiconductor diodes and a plurality ofmanually operated, singlepole, double-throw switches arranged in equalgroups, one group for each group in said second switching means, thefixed terminals of all switches in each group being connected inparallel, each set of fixed terminals being connected to a DC, source,the movable arms of all switches being arranged to operate in equalsets, each set containing one switch from each group, each of themovable arms of one set being connected mechanically to a movable arm ofa switch in one set of switches in said second switching means andfurther connected to ground, the movable arms of each of all other setsbeing connected in parallel and further connected through one of saidsemiconductor diodes to one of the 0 through 9 cathodes of the numeralindicator tube in said second display means; fourth switching means forselecting the digit displayed by said second display means in theGCTONARY- BINARY and DECIMAL-BINARY operating modes comprising amanually operated rotary switch having a plurality of positions and aplurality of decks, a separate position being provided for the BINARYoperating mode and each of the 0 through 9 cathodes in said seconddisplay means; and voltage measuring means for said third switchingmeans comprising a plurality of test points, one connected to each ofthe 0 through 9 cathodes of the numeral indicator tube in said seconddisplay means and one at the point of connection of each of said movablearms with one of said semiconductor diodes. 3. In a training device fordemonstrating the binary number system, the combination comprising:

display means for visual display of digits in the binary number systemcomprising a plurality of numeral indicator tubes, each having means fordisplaying the digits 0 and l;

first switching means that connect a D.C. source to said numeralindicator tubes; 7

second switching means for selecting the combination of digits displayedby said numeral indicator tubes comprising a plurality of manuallyoperated singlepole, double-throw switches, one for each said numeralindicator tube, one fixed terminal of each switch being connected to theO cathode and the other fixed terminal of each switch being connected tothe l cathode of one of said numeral indicator tubes; and

third switching means for causing said numeral indicator tubes todisplay the combination of digits selected by said second switchingmeans comprising a plurality of manually operated switches, one switchfor each switch in said second switching means, the fixed terminal ofeach switch in said third switching means being connected to the movingarm of a switch in said second switching means, the moving arm of eachswitch in said third switching means being connected to ground.

4-. Apparatus according to claim 3, wherein second display means forvisual display of digits in the octonary and decimal number systems, isa numeral indicator tube having means for displaying the digits 0through 9 suitably connected to a DC. source by said first switchingmeans, and with the 8 and 9 cathodes disabled by said first switchingmeans; and

fourth switching means for selecting the digit displayed by said seconddisplay means comprising a plurality of semiconductor diodes and aplurality of manually operated, single-pole, double-throw switchesarranged in equal groups, one group for each switch in said secondswitching means, the fixed terminals of all switches in each group beingconnected in parallel, each set of fixed terminals being connected to aDC. source, the movable arms of all switches being arranged to operatein equal sets, each set containing one switch from each group, each ofthe movable arms of one set being connected mechanically to a movablearm of a switch in said second switching means, and further connected toground, the movable arms of each of all other sets being connected inparallel and further connected through one of said semiconductor diodesto one of the through 7 cathodes in said second display means. 5.Apparatus according to claim 4 in which the 8 and 9 cathodes of saidsecond display means are enabled by said first switching means byconnecting each of said 8 and 9 cathodes through said semiconductordiodes to the anovable arms of a set of switches in said fourthswitching means.

6. In a training device for demonstrating conversion of digits in theoctonary number system to digits in the binary number system, thecombination comprising:

first display means for visual display of digits in the binary numbersystem comprising a plurality of numeral indicator tubes, each havingmeans for displaying the digits 0 and 1;

second display means for visual display of digits in the octonary anddecimal number systems comprising a numeral indicator tube having meansfor displaying the digits 0 through 9;

first switching means that connect a DC. source to said first and seconddisplay means and disable the 8 and 9 cathodes in said second displaymeans;

second switching means for selecting the combination of digits displayedby said first display means comprising a plurality of manually operatedsingle-pole, double-throw switches arranged in equal groups, one groupfor each numeral indicator tube in said first display means, the fixedterminals of all switches in each group being connected in parallel, oneset of fixed terminals being connected to the 0 cathode and the otherset of fixed terminals being connected to 8 the 1 cathode of a numeralindicator tube in said first display means, the movable arms of allswitches being arranged to operate in equal sets, eachset containing oneswitch from each group;

third switching means for selecting the digit displayed by said seconddisplay means comprising a manually operated rotary switch having aplurality of positions and a plurality of decks, the moving arm of eachdeck being connected to ground, a position being provided in each deckfor each of the 0 through 9 cathodes in said second display means,corresponding positions in one deck being connected to the 0 through 7cathodes eachof corresponding positions in each of all other decks beingconnected to the moving arm of a switch in a group of switches in saidsecond switching means.

7. Apparatus according to claim 6 in which the 8 and 9 cathodes of saidsecond display means are enabled by said first switching means byconnecting said 8 and 9 cathodes to positions 8 and 9 in one deck ofsaid third switching means.

References Cited by the Examiner UNITED STATES PATENTS 2,665,070 1/54Avery 235-155 X 2,928,600 3/60 Fleming 235-155 3,027,080 3/62 Thorsson235155 3,055,121 9/62 Neal .a -31 JEROME SCHNALL, Primary Examiner.GEORGE A. NINAS, In, Examiner.

1. IN A TRAINING DEVICE FOR CONVERSION OF NUMBERS FROM ONE SYSTEM TOANOTHER IN THE BINARY, OCTONARY, AND DECIMAL NUMBER SYSTEMS, THECOMBINATION COMPRISING: FIRST DISPLAY MEANS FOR VISUAL DISPLAY OF DIGITSIN THE BINARY NUMBER SYSTEM; SECOND DISPLAY MEANS FOR VISUAL DISPLAY OFDIGITS IN THE OCTONARY AND DECIMAL NUMBER SYSTEMS; FIRST SWITCHING MEANSFOR PROVIDING A PLURALITY OF OPERATING MODES AND CONNECTING A D.C.SOURCE TO SAID FIRST AND SECOND DISPLAY MEANS; SECOND SWITCHING MEANSFOR SELECTING THE COMBINATION OF DIGITS DISPLAYED BY SAID FIRST DISPLAYMEANS; THIRD AND FOURTH SWITCHING MEANS FOR SELECTING THE DIGITDISPLAYED BY SAID SECOND DISPLAY MEANS; AND VOLTAGE MEASURING MEANS FORSAID THIRD SWITCHING MEANS.